1. Field of the Invention
The present invention relates to a machine which compresses or conveys fluid and can be used as a compressor, pump, or actuator.
2. Discussion of the Related Art
A known machine compresses or conveys fluid by making use of changes in the volume of a compression chamber formed by a moving means and the inner wall of a casing, the changes being brought about by movement of a movable body. The movable body consists of a diaphragm in the casing. A diaphragm type pump in which a diaphragm is used as the movable body is disclosed in Japanese Patent Laid Open No. 246569/1988.
The flow resistance at the intake side in the compression machine significantly reduces the volumetric efficiency of the compressor even if the resistance has a low value, so that the flow resistance has a great influence on the performance of the compression machine.
To reduce the flow resistance, it has been known to enlarge the area of the flow passageway, but this results in an intake valve of a large size and the operation characteristics of the compressor are degraded at high rotation speeds due to valve inertia. Moreover, the conventional compression machine may be of cylindrical form and cannot accept a large valve, and the enlargement of the flow passageway is wasteful.
Thus, in the diaphragm pump disclosure in the above-mentioned publication, the intake resistance at the valve portion is high and the volumetric efficiency is poor.